Abstract The ultimate goal of the proposed project is to develop a commercial illumination device, detection system kit and original ELISA diagnostic kits for detection of HIV p24 antigen in human serum or plasma by a photochemical amplification method (PAM) developed within Phases I and II. The methods for identifying HIV infection include HIV antibody tests, viral isolation through viral culture, nucleic acid tests to detect viral RNA, tests to detect viral p24 antigen and tests to detect the viral enzyme reverse transcriptase. These methods are highly specific, and a positive result almost always confirms infection. However, each has limitations, and their use must be tailored to proper testing situations. Tests for viral nucleic acid have been introduced but require sophisticated technology, dedicated and well-trained personnel, and are very expensive. Tests to detect p24 antigen are simpler to perform than nucleic acid tests and offer alternatives for monitoring HIV infection. The p24 antigen test also can be of value in blood screening, for identification of acute infection, to assist in the diagnosis of infection in the newborn, and in detecting antigen in supernatants from cultures that have been inoculated with cells from a patient suspected of being infected. At present, p24 antigen tests are relatively insensitive, being able to detect only 5-20 pg/ml. This quantity of antigen may not be present in the serum of infected individuals, even when the virus is actively replicating. Therefore, development and the use of more sensitive p24 antigen tests has a great relevance. It is in this context that in Phases I and II we developed highly sensitive p24 antigen assays that are less expensive than RNA viral load tests and appropriate for use both in developed and developing countries in which the limitations of infrastructure and laboratory capability prohibit nucleic acid testing. The specific aims of Phase IIB Competing Renewal are: 1. To design and manufacture a pre-production PAM illumination device. 2. To design and develop a PAM detection system kit, HIV p24 ELISA kit and fourth generation ELISA kit for HIV detection as ready-to-use ELISA + PAM diagnostic kits. 3. To perform pre-clinical studies in accordance with FDA Regulatory pathway using over five hundred clinical samples.